Item in dependability: definition and content of the concept

Abstract

Aim.The paper continues the series of publications that investigate and discuss the essence and definitions of the basic concepts of the dependability theory. It analyzes the basic concept, which is the subject of consideration in dependability, for which the term “item” is usually used. The concept of “dependability” is defined for it, and in general all the terminology of dependability applies to it. The following issues are considered: how to name and define this subject of consideration, what it can be, what can be its constituents. In particular, the relationship between the concepts of “item” and “product” is discussed.Methods.The evolution of definitions of this concept in the Russian and international terminological standards in dependability over the past 30 years is traced. A comparative analysis of other standards and federal laws relating to items of different types is carried out. The viability of two main ways of getting an idea of a concept is considered: illustrative (based on examples) and definitional (by means of sequential definition of some concepts through others).Findings and conclusions.The definition and correct understanding of the concept of “item” is of great importance, as it affects the scope of dependability standards. It is explained why it is necessary to accept that the definitions of the basic concepts cannot be rigorously formalized and are in fact only explanations. It is shown that the definitions of the item in the existing Russian and international standards (GOST 27.002–2015 and IEC 60050-192:2015) have inaccuracies. To eliminate them, improved notes to the definition of an item are proposed. The first note lists the possible types of items: products (parts, assembly units, complexes) and their components; buildings and structures; systems consisting of jointly functioning products and structures and their subsystems. The second note indicates the relationship between the main constituents of the item: hardware, software and people (personnel), and their possible combinations. The paper provides reasons for considering virtual items that play an important role in today’s information and telecommunication technologies and are logically isolated subsystems within the systems that they are part of. Besides that, it points out the deficiencies in the definitions of various items in GOST 18322–2016.